Most of the career incentives in the paleoanthropology business encourage scientists to declare whatever piece of ancient skull they dig up represents a new species previously unknown to science, or even a new genus.
But what does it mean to say that two bones from different eras represented different species? We barely have a workable definition of species for living creatures. Ernst Mayr's definition — can and/or will two individuals mate and produce fertile offspring — is about the best we've got, and it has obvious problems. (For example, are dogs, coyotes, and wolves different species or not? If they are all one species, should the Endangered Species Act apply to wolves? What about the protected Red Wolf, which is actually part coyote? Etcetera etcetera).
By JOHN NOBLE WILFORD
After eight years spent studying a 1.8 million-year-old skull uncovered in the republic of Georgia, scientists have made a discovery that may rewrite the evolutionary history of our human genus Homo.
It would be a simpler story with fewer ancestral species. Early, diverse fossils — those currently recognized as coming from distinct species like Homo habilis, Homo erectus and others — may actually represent variation among members of a single, evolving lineage. In other words: just as people look different from one another today, so did early hominids look different from one another, and the dissimilarity of the bones they left behind may have fooled scientists into thinking they came from different species.
In other words, different races existed back in Ye Olde Days, just like today. Of course, that, in turn, raises the question of "What is a race?"
... Dr. Lordkipanidze and his colleagues said the differences between these fossils were no more pronounced that those between any given five modern humans or five chimpanzees. The hominids who left the fossils, they noted, were quite different from one another but still members of one species.
Or maybe not. Maybe they wouldn't breed together because they disliked each other's smell. Who knows?
Yet, all these inherent uncertainties doesn't mean Species Does Not Exist